Patent EP-A-3192 describes a clamp fitting constituted by a metal band, wound on itself, of which one of the ends presents an ear projecting radially on the outer periphery of the clamp and of which the other end is shaped as a hook capable of hooking behind the ear to maintain the clamp tightened.
It is known that one of the principal advantages of this prior-art clamp is that of avoiding, in principle, any permanent deformation of the various zones of the band which constitutes it, when it is positioned and tightened.
This type of clamp has already been improved in various ways. On the one hand, Patent EP-A-344 050 proposes to facilitate tightening of the clamp thanks to a boss disposed on the face of the ear serving as bearing for the free edge of the hook when the clamp is in tightened position. On the other hand, certain improvements aim at giving the clamp a reserve of elasticity enabling a sufficient tightening to be maintained in the event of modification of the dimensions of the object to be clamped, in particular under the effect of the variations in temperature. In this respect, reference may be made to Patents EP-A-469 989, 491 609 or 491 610.
However, it has been realized that, in certain difficult cases, the quality of the clamps described in the Patents mentioned above risk being lost if precautions are not taken when said clamps are placed in position or tightened.
More precisely, when hooking the hook on the ear, the operator may inadvertently provoke a temporarily too great tightening of the clamp. In particular, such excessive tightening is not prevented by the guiding or reinforcing ribs located on the face of the ear opposite the hook-bearing zone, as described in the Patents mentioned above or visible in the drawings accompanying same. This results in that, in certain zones of the clamp, particularly in the reserves of elasticity or in the regions of considerable curvature of the hook itself, the limit of elasticity of the metal is exceeded. Thus, without the operator being able to avoid it, the pressure of tightening of the clamp after it has been positioned is less than that for which the use of the clamp had been recommended by the installer and its dimensional characteristics had been determined by the manufacturer. Such a situation exists in particular in the automobile industry and may lead to serious incidents, particularly if the clamp is intended to ensure tight connection of a flexible pipe fitted on a rigid tube.
It is therefore an object of the present invention to avoid, on the clamps of the types mentioned above, any exceeding of the limit of elasticity of the metal in any zone of the clamp, during positioning and tightening thereof. However, it goes without saying that this problem is to be solved only in the case of a clamp whose dimensional characteristics and the metal of the band are adapted to a determined use and provided therefor.